An ethical hacker is hired to evaluate the defenses of an organization's database system which is known to employ a signature-based IDS. The hacker knows that some SQL Injection evasion techniques…

Utilizing `CHAR()` or `ASCII()` encoding functions allows attackers to construct SQL commands where the malicious strings (like table names, column names, or keywords) are represented as hexadecimal or decimal values. A signature-based IDS, which relies on matching predefined literal patterns, will often fail to detect these dynamically constructed strings because the actual malicious string is not present in its literal form within the query text until executed by the database engine.

Implementing slightly varied but still common SQL injection tautologies like "OR john' = 'john'" is unlikely to bypass a sophisticated signature-based IDS designed to detect common SQL injection patterns.

Manipulating white spaces, while a form of obfuscation, is generally a basic evasion technique and less likely to bypass a modern or advanced signature-based IDS which often normalizes or accounts for whitespace variations.

URL encoding is an HTTP-level encoding method primarily handled by web servers or WAFs; the database system's IDS would typically receive the decoded SQL query, or the query would fail if not properly decoded before reaching the database.